Electrical thermostat



April 24, 1934.

W. D. HARPER ELECTRICAL THERMOSTAT 2 Sheets-Sheet l Filed June 2l,v 1953 nvenlor W. D Haffner April 24, 1934.

W. D. HARPER Filed June 21, 1933 ELECTRICAL ATHERMOS TAT W. Harper 2 Sheets-Sheet 2 nvenfor Patented Apr. 24, 1934 UNITED STATES PATENT OFFICE 1 Claim.

This invention appertains to new and useful improvements in the general art of electric switches, and more particularly to anovel thermostatic switch for controlling electrical circuits.

5 The principal object of the present invention is to provide a thermostatic switch employing a liquid thermal element in conjunction with a pair of contacts, one of which can be adjusted in proportion to the temperature at which the liquid l is to engage the same.

Other important objects and advantages will be found after reading the following specification.-

In the drawings:-

15 Figure 1 represents a side elevational view of the thermostatic switch, with an alarm device connected thereto.

Figure 2 represents a top plan view of the structure shown in Figure 1.

Figure 3 represents a vertical sectional view taken substantiallly on line 3-3 of Figure 2.

Figure 4 represents a top plan view of the thermostatic switch with the dome removed.

Figure 5 represents a cross sectional view taken substantiallly on line 5 5 of Figure'3.

Figure 6 represents a diagrammatic view disclosing the electrical connections between the electrical devices involved.

Referring to the drawings wherein like nu- 80 merels designate like parte, it een be seen that numeral 5- represents a shell of metal having a depending tubular extension 6 with perforations 7 therein. This tubular extension 8 is closed at its bottom and has the narrow or reduced exten- 35 sien s ef the dielectric body 9 disposed inte the same. The lower end portion of the extension 8 is provided with a pocket v10 in which is located a deposit 11 of mercury or some other suitable 40 temperature responsive matter. Extending from this pocket 10 is a duct 12 which extends upwardly to the larger bore 13 which opens through the top of the body 9.

The upper portion of the shell 5 is internally reduced and threaded to receive the lower threaded end of the dome 14. The upper portion of the shell 5 is further internally threaded to receive the threaded annulus l'which serves as a iamb nut to bind the 'metallic ring 16 and dielectric disk 17 against the top lof the body 9. A.

bolt 18 is threaded vertically through the dielectric y,disk 17 and has a bore therethrough through which the threaded stem 19 is feedable. The upper end of this stem 19 is provided with a head 20 having a screw driver slot 2l therein and beneath this head 20 is a dial 22 suitably secured to the stem 19. The lower portion of the stem is provided with a needle like extension 23 o which depends into the duct 12 and has a needle (Cl. 20o-141) pointed lower end with which the liquid deposi 11 is engageable.

Numeral 24 represents a contact rod, the lower end of which projects into the chamber 10, while its upper end extends through the di-electric disk 17 to have the conductor 25connect thereto. A nut 26 on the stem 19 binds the plate 27 to the bolt 18 and this plate 27 has a lug to which the other conductor 28 is secured. The metallic annulus 1,6 has an upstanding graduated rod 29 which is laid off in temperature degrees and is complementary with respect to the dial 22. As the dial 22 rises or lowers with the feeding action of the stem 19, the dial 22 will correspond to the different degrees on the gauge rod 29 at which the thermal liquid 11 will reach the contact 23.

Numeral 32 represents a perforated shell in which a lamp 33 or some other suitable electrical alarm or signal is mounted. vNumeral 34 represents clamps on the shell 32 for engagement around the shell 5 of the thermostatic switch. Numeral 35 represents a current supply line across which the conductors 25-28 are connected.

While the foregoing specification sets forth the invention in specinc terms, it is to be understood that numerous changes in the shape, size and materials may be resorted to without departing from the spirit and scope of the invention as claimed hereinafter.

Having described the invention, what is claimed as new is:-

A thermostatic switch comprising a di-electric body having pockets within the opposite end portions thereof, one of said pockets containing a quantity of conductive liquid, said pockets being connected by a duct, the other pocket affording an overflow space for liquid rising in the duct, a protective shell encasing the body, said shell being provided with an open end, said open end portion being internally threaded, the overow pocket opening through one end of the body, a ,di-electricouter end, beiner provided with a handle wherebyA it can be turned in adjusting the needle in the duct.

WALTER DUSENBURY HARPER. 

